1. Field of the Invention
The present invention relates generally to an oil pump for an automatic transmission and, more particularly, to a gear pump for a transmission including a pump having teeth formed to a thickness which varies randomly from a baseline thickness.
2. Discussion
A typical automatic transmission utilizes transmission fluid or oil under pressure to lubricate and dissipate heat from the transmission components and to effect engagement and disengagement of planetary gear sets. A gear pump located within the automatic transmission provides the fluid pressure that enables operation of the automatic transmission. Typical gear pumps utilize a drive pump gear which meshes with at least one driven gear. The gear pump receives fluid at an input pressure, and the drive and driven gears cooperate to create fluid pressure at an outlet which is utilized to operate the automatic transmission.
The pump gear of the oil pump typically includes a cylindrical bore which engages the rotor of the torque converter or other input drive element at the input side of the transmission. The cylindrical bore supports a central section or base circle of the pump gear. The central section in turn supports a plurality of gear teeth. Typical pump gears include gear teeth which are formed of uniform thickness and are spaced uniformly apart. It has been determined that such an arrangement causes operation at resonance frequencies which create undesirable audible noise to emanate from the automatic transmission.
Thus, it is an object of the present invention to provide a gear pump for an automatic transmission which generates minimal noise.
It is yet a further object of the present invention to provide a gear pump configured to eliminate operation at a resonant frequencies.
It is yet a further object of the present invention to provide a gear pump for an automatic transmission having a pump gear in which the thickness of the gear teeth varies randomly from a baseline thickness.